1. Field of the Invention
The present invention relates to a synthetic resin molded article having a good and durable antistatic property and to a process for the preparation thereof.
2. Description of the Related Art
Although many synthetic resin molded articles commercially available at the present have various excellent properties, since they generally have a high electric resistance value, they are easily charged by friction or the like and dust and dirt are readily attracted to the surface thereof to degrade the appearance characteristics.
As means for imparting an antistatic property to a synthetic resin molded article, there can be mentioned (1) an internal addition of a surface active agent; (2) a surface coating with a surface active agent; (3) a surface coating with a silicon compound; and (4) a surface modification by a plasma treatment. Since methods (3) and (4) are expensive, methods (1) and (2) are generally adopted.
In the method of internal addition of a surface active agent, since the surface active agent is incorporated or dispersed into the resin-forming starting material before the polymerization or into a synthetic resin before the molding, the preparation steps can be simplified. However, in order to obtain a desired antistatic property, it is generally necessary to increase the amount of the surface active agent added, and if the amount of the surface active agent is increased, the inherent mechanical characteristics of the synthetic resin are degraded and the obtained antistatic property is readily lost by water washing or friction.
In the method of the surface coating with a surface active agent, the physical properties of a synthetic resin as the base material are not degraded and a satisfactory antistatic property can be obtained with a small amount of the surface agent. However, since the coating step is necessary, the cost is increased and there is a possibility that the inherent beautiful appearance is degraded. Also, the antistatic property is easily lost by water washing or friction.
As is apparent from the foregoing description, a synthetic resin molded article having a good and durable antistatic property and retaining the inherent physical properties of the synthetic resin has not been proposed.